Telephone system



(No Model.)

"W,- GOONAN. TELEPHONE SYSTEM.

Patenteli Apr. 23, 1895. I09 2 mum/roe William bomiz/ ASHINGTON, u. c

we cams pz-rcn's co. PHOTCLLITHCL. w

NITED STATES i ATENT Free.

\VILLIAM COONAN, OF JERSEY CITY, ASSIGNOR TO HIMSELF, AND WM. A. CHILDS, OF ENGLEVVOOD, NElV JERSEY.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 537,967, dated April 23, 1895.

Application filed August 4, 1892. $erial No. 442,131. (No model.)

To call whom it may concern:

Be it known that 1, WILLIAM COONAN, a subject of the Queen of Great Britain, residing at Jersey City, in the county of Hudson and State of New Jersey, have invented certain new and useful Improvements in Telephonic Systems, of which the following is a full, clear, and exact description.

Thisinvention relates to telephonic systems, and has special reference to means whereby the operator at the exchange may determine whether a subscriber called for is busy or not. This operation is commonly known as testing, and many different ways of making this test have been devised.

The object of my invention is to provide a test in which the indication of busy or free is made by an instrument having no effect upon the subscribers line.

A further object of the invention is to provide a test apparatus which is simple, quick and easy to manipulate.

The invention consists of the method and details of construction which will be hereinafter described and claimed.

In the accompanying drawings, Figure 1 represents a diagram of the circuits. Fig. 2 represents an external view of the circuit controller to be held in the hand of the operator. Fig. 3 represents alongitudinal section of one end of the circuit controller. Fig. 4 is a transverse section of the same taken on line ab of Fig. 2.

Fig. 6 is a side elevation of the test magnet.

Referring to the drawings by letters and figures, A represents a magneto generator.

B represents a test magnet. It consists of two magnets 19 and b respectively acting in opposition to each other upon an armature b pivoted in the middle at 12 The number of turns and size of wire on the magnetb is such as to give it about one hundred ohms resistance, and the number of turns on magnet b is such as to give it about twelve hundred ohms resistance. In series with the magnet b is a further artificial resistance of say four thousand eight hundred ohms. A spring 12 acts upon the armature b in opposition to the high resistance magnet 19'.

Fig. 5 is a similar section taken on line cd of Fig. 2.

G is a handle of hard rubber or other insulating material which is held in the exchange operators hand. This handle is provided on its under side with a longitudinal groove c,in which is placed a key 0' hinged at the point 0 and carrying a brass strip 0 which projects at one end and carries two contact points as shown. A spring 0 bears against the back of the key with a tendency to force it outward. Two stops or contacts 0 0 respectively are fixed in the end of the handle, and are provided with suitable means for connecting electrical conductors, and forming circuit terminals with which the end of strip 0 is adapted to engage. Two conductors 12 and 1 connected together in a flexible cord 0 lead respectively from these terminals to the operators speaking instrument D and the magneto generator A. At the opposite end of the handle two other conductors 8 and 10 located together in a flexible cord 0 pass through suitable openings in the end of the handle, and in the key, and lead out through a hole 0 in the face of the key to the two points of a double contact plug I. The cord connecting the handle to the plug is short, so that the plug is within easy reach and may beheld by the fingers of the hand which grasps the handle. The two conductors 8 and 10 lead back from the plug to the magnets 19 and b respectively. The two flexible cords c and c are joined together in a single flexible cord 0 and thence pass to the different points mentioned. The brass strip 0 is connected to Wire 10 by the short wire 0.

D represents the operators speaking instruments which are connected on one side by wire 12 with the contact point 0 in the handle and on the other side'by wire ll with wire 8 leading to one of the contacts in plug I.

The operation is as follows: When a subscriber calls for a connection, central operator puts plug I into a socket of the switchboard corresponding to the subscriber wanted, and squeezes key 0 in. This socket is represented in Fig. l by e, and it contains two contact pieces forming the terminals of the subscribers circuit. The two terminals of the plug make contacts respectively with the terminals of the subscribers circuit and ICO establish the following path for the magneto current generated by A: from generator A by wire 1, contact o strip 0 to the point 2 where it divides, a portion" going by wire 3, plug and socket, called subscribers wire 4, and, when the called subscribers telephone is on the hook, or is in its normal position, the current flows through wire 5, bell magnet 6, artificial resistance of about fifteen hundred ohms, subscribers hook switch, wire 7, plug e, wire 8, test magnet b, wire 9 to the generator. From the point 2 where the current divides, the other portion flows over the wire 10, test magnet 1), wire 11 and generator. Now, the subscribers bell magnet 6 and the artificial resistance, being in circuit and adding a large resistance to the line, there will be a comparatively small amount of current flowing through the test magnet b, and therefore a comparatively large amount of current flowing through test magnet b. Intact these magnets are wound so that when the subscribers circuit. and bell magnet, are in circuit the ampere-turns of test magnet b will be less than the ampere-turns of test magneto. Consequently I) will pull down the armature with each impulse of current, and between the impulses the spring 6 will pull the armature in the opposite direction, the result being a fluttering or buzzing of the armature W. This fluttering which is audible to the operator is the indication-toher that the called subscribers line is free. Operator then releases key 0, which puts her telephone into circuit with the called subscriber. When subscriber answers opera-tor may connect the two subscribers together by any means at her disposal. In case the called subscriber is already connected with any other subscriber on the switchboard, then, the joint resistance of the two lines, being much lower than the resistance of either one of them, more of the current will flow from the point 2 over the subscribers lines and through the test magnet b, so that, the ampere-turns of b will be more than those of b. b then acting in conjunction with the spring 6, will attract the armature and hold it stationary. Silence will therefore be the indication to the opera tor that the called subscriber is busy. It will be observed that this test is made without the use of the speaking instruments and the loud and objectionable click or noise which is, caused by a battery current acting upon the callingsubscribers receiver is therefore not experienced. The line itself is used as part of the test circuit, and the Whole apparatus is simple, and quickly and conveniently operated.

Having thus described my invention, I claim- 1. In telephone exchange systems, a testing apparatus consisting of two electro-magnets of difierent, resistances, connected in parallel and acting in oppositionoupon a. pivoted armature, in combination with a switching apparatus and a subscribers line, said. switching apparatus being arranged to connect the subscribers line in series with one of said magnets, substantially asdescribed.

2. In telephone exchange systems, the combination with a subscribersline, an artificial resistance and a bell magnet therein at subscribers statioma switch arranged to cut said resistance out and leave. the line closed, a central office testing apparatusconsisting oftwo electro-magnets of different resistances, connected in parallel, an operators switchingapparatus and means whereby the subscribers line may be connected in series with one of said magnets, substantially as described.

In testimony whereof I subscribe my signature in presence of two witnesses.

W'ILLIAM COONAN.

Witnesses:

WM. A. RosENBAU-M, J os. J UHL. 

